Oleksandr Serpokrylov and Dmytro Zaitsev appeared before the Northern Ireland High Court by video-link on Tuesday to defend contempt of court proceedings over a USD$45m claim against a shopping centre in Kiev.
Lawyers for the Irish Bank Resolution Corporation (IRBC) claim the two men, as representatives of a mysterious offshore company, ignored an injunction against any transfer of debts surrounding the mall.
IBRC, the former Anglo Irish Bank, has been seeking control of Mr Quinn's international empire in an attempt to recoup more than €2bn.
As part of the wider legal battle the British Virgin Islands-registered Lyndhurst Development Trading was prohibited from enforcing any loan agreement under the terms of an emergency injunction granted in Belfast last December.
It is alleged that later the same day the order was ignored at a hearing in Kiev.
Lyndhurst secured judgment from the Ukrainian court that it was entitled to enforce a $45m debt against the firm which owns the mall, Univermag.
A judge in Belfast has already ruled that the property debt was transferred from one of Mr Quinn's companies to put it beyond the reach of IRBC.
Mr Justice McCloskey held earlier this year that those responsible for the loan assignment were "indulging in an orchestrated, elaborate and illicit charade".
All disputed transactions were declared null and void, with control returned to the former Anglo Irish Bank.
A chain of assignments scrutinised in the case set out how Fermanagh-based firm Demesne Investments, of which Mr Quinn is a former director, had been owed $45m by Univermag.
But in April 2011, Demesne transferred its rights to the debt to Innishmore Consultancy, another Northern Ireland company run by Mr Quinn's nephew Peter Darragh Quinn.
From there the loan was moved on to Lyndhurst last October.
Lawyers for IBRC argued that the assignment was a sham, part of an asset-stripping exercise carried out at a massive undervalue and not worth the paper it was written on.
Despite securing judgment, they have pressed ahead with contempt of court proceedings against Mr Serpokrylov and Mr Zaitsez.
If the two defendants are found guilty, they could be jailed.
But with both men remaining in the Ukraine, any such outcome is unlikely to be enforceable while they remain outside the European Union.
Cross-examining Mr Zaitsev, an economist, Gabriel Moss QC, for the bank, on Tuesday asked if the $45m was never agreed as the price of the transfer.
But the defendant insisted: "It was an agreement about price and it was $45m."
He said Peter Quinn was involved in what was described as a "silent arrangement".
Speaking through an interpreter, Mr Zaitsev added: "This money, this sum, was related to the paper assets and I don't know exactly what is the market price of these paper assets at the minute."
Mr Moss replied: "The assets have no value, Mr Zaitsev, have they?"
The witness told him he did not understand.
At one stage his barrister, Brett Lockhart QC, interrupted the questioning to claim the hearing was moving away from its purpose.
He told Mr Justice McCloskey: "This is about the failure of Mr Zaitsev to not proceed with the court (in Kiev) on December 23.
"We now seem to have extended the ambit of this inquiry much further beyond that."
The case continues.